1. Field of the Invention
The present invention relates to data storage apparatus for magnetically read and writing information on data storage media. More particularly, the invention concerns the interconnections of termination pads and leads in disk drive Integrated Lead Suspension (ILS) assemblies that mount micro-actuators with attached air bearing sliders.
2. Description of the Prior Art
By way of background, a read/write transducer of a magnetic disk drive storage device is typically mounted on an air bearing slider that is designed to fly closely above the surface of a spinning magnetic disk medium during drive operation. In older drive designs, the slider is mounted directly on a suspension assembly that is cantilevered from the arm of a pivotable actuator. More recently, micro-actuators have been proposed which facilitate fine positioning adjustments to help maintain the transducers above track centerlines.
A disk drive suspension assembly conventionally includes a load beam that attaches to the actuator arm and a flexure assembly that mounts to the load beam and carries the slider in a gimbaled arrangement. In an ILS assembly, the flexure assembly incorporates a laminated conductive lead system for interconnecting the transducer and the disk drive read/write electronics. If the suspension is to include a micro-actuator, there will also be leads to control micro-actuator positioning. Each of these leads must be properly connected at the slider end of the suspension assembly. For that purpose, two levels of electrical terminations are made. At the first level, there will be four terminations between the slider and the micro-actuator to electrically connect the read transducer (two connections required) and the write transducer (two connections required). At the second level, there will be eight terminations between the micro-actuator and the conductive leads of the ILS assembly. Four terminations are associated with the read and write sensors, and four terminations are associated with positioning the micro-actuator itself. In all, twelve terminations need to be made at the first and second levels.
The four slider-to-micro-actuator interconnections and the eight micro-actuator-to-ILS interconnections could possibly be made using a conventional wire bonding method. However, there are serious drawbacks in using this approach, to wit: a) a wire bonding process applies pad forces on the order of 100 grams, which is well beyond the 1-2 gram force that the fragile micro-actuator pads would be able to withstand; and b) the handling of eight fine wires to be attached to the micro-actuator would be extremely difficult in manufacturing.
Another possible slider/micro-actuator connectivity approach would be to use ultrasonic bonding of ILS bent leads, where the ends of the leads are bent into a plane that is generally parallel to the plane of a set of electrical terminal pads formed on the micro-actuator side edge. Again, there are serious drawbacks with this approach, to wit: a) the process of making the micro-actuator does not provide a method of forming pads on the side edge; and b) ultrasonic bonding also requires approximately 100 grams of force on the micro-actuator.
In light of the foregoing, an improved slider/micro-actuator connection approach is indicated. What is required is a new termination configuration and method in which a) hard wiring of the slider and micro-actuator is not required, b) wire bonding is avoided, and c) electrical terminals do not have to be placed on micro-actuator side edges.
The foregoing problems are solved and an advance in the art is obtained by an improved method of forming electrical interconnections between the leads of a disk drive suspension assembly and a micro-actuator mounting a transducer-carrying slider. According to preferred implementations of the method, a first set of termination pads is provided on a generally planar surface of the micro-actuator that is generally orthogonal to a front edge portion of the micro-actuator. The first set of termination pads is located adjacent to the micro-actuator front edge portion. A set of leads is provided on the suspension assembly so as to extend generally orthogonally to the first set of termination pads and in adjacent relationship therewith. Electrical connections are provided between the first set of termination pads and the suspension assembly leads, preferably by soldering, and most preferably by placing solder elements in mutual contact with the first set of termination pads and the leads and heating the solder elements to form a solder bond. This heating can be performed by laser and without large forces on the first set of termination pads.
Preferably, the suspension assembly leads are parallel to and in spaced adjacent relationship with the micro-actuator front edge portion. They can be made to terminate slightly beyond the micro-actuator generally planar surface and the adjacent first set of termination pads.
The method of the invention may further include providing a second set of termination pads on the micro-actuator generally planar surface in spaced relationship with the first set of termination pads and adjacent to a front edge portion of the slider. A third set of termination pads may be provided on the slider front edge portion. The second and third sets of termination pads are electrically connected. A solder element soldering method with laser heating may be used for this purpose. Preferably, the second set of termination pads is generally orthogonal to the third set of termination pads.
If desired, the first set of termination pads and the suspension assembly leads may be arranged in two groups that are spaced from each other along the micro-actuator front edge, such as on each side of the second set of termination pads and the third set of termination pads.
Note that both the first set of termination pads and the second set of termination pads are preferably formed as part of a thin film process used to fabricate the micro-actuator so as to avoid damage to the micro-actuator which could otherwise result if the termination pads were formed on the micro-actuator subsequent to its fabrication.
The invention further contemplates a suspension assembly and a disk drive that incorporate an improved termination system made in accordance with the above-summarized method.